How Does Your Garden Grow? Chemicals in Agriculture

A weed is a plant that is growing where it is not wanted They can be a NUISANCE They can be a HAZARD They can cause injury, such as poison ivy They can compete with garden plants for soil nutrients, light and water. They can harbor insects and disease pests Weeds

Ways to Eliminate Weeds Pulling them out of the ground manually from their roots Mowing and clipping weeds to slow their growth Mulching, or covering the soil with a material to prevent light from reaching weed seeds. Chemical herbicides

What Are Herbicides? Herbicides are chemicals that are sprayed on the garden used to kill weeds They are generally a last resort for home gardeners They have several advantages and disadvantages

Advantages of Herbicides They kill unwanted plants. Most of the time one application of the herbicide is enough whereas other methods have to be continually used. They are easy to use They work fast and can be removed quickly in critical situations. Herbicides are relatively cheap, and most of the time cheaper than manual weeding. They can destroy plants bearing diseases. They help the crops grow by destroying the weed that is robbing the crops of water, nutrients and sunlight. Some are biodegradable, and become relatively harmless after a period of time.

Disadvantages of Herbicides Some herbicides are non-biodegradable and are harmful for a long period of time. They are all slightly toxic. They can cause illnesses. Some can cause eye and skin problems and upper respiratory effects in the user or irritations to the skin and may also lead to death. They can be carried into streams by runoff rainwater or leached into underground water supplies polluting them. Herbivores may eat the plants treated with herbicides and then carnivores eat the herbivores. The toxic herbicide would be passed up the food chain increasing in concentration each time resulting in cancers and even deaths.

Herbicide Regulations Farmers that are spreading large amounts of herbicides are often required to apply for a permit The permit will tell the farmer what they are allowed and not allowed to do very specifically The farmer must send in a report after using the herbicide

Permit Considerations When the government is considering issuing a permit to a farmer who is planning on applying herbicide to a large area, they will consider the following – wind speed and direction at time of application – temperature at time of application – field location and quantity of acreage – time of application – grower name, address and phone number – owner/operator firm name, address and phone number – applicator name, address, phone number and certification number – product name and EPA registration number

Herbicide Control Equipment Large-scale applicators often use aerial equipment such as helicopters or large machinery (such as tractors) that sprays herbicide to cover large areas of land. For more personal use, smaller applicator machines are available

Examples Aerial application Large-scale Machine application Personal application

Garden Pests Insects and or animals that damage and consume crops and garden plants Examples: – aphids, slugs, weevils, and wireworms, earwigs, mealy bugs, rabbits, squirrels, grasshoppers Many farmers use pesticides to get rid of these unwanted pests.

What are Pesticides? Pesticides are chemicals that are used to control or kill the pests that live in gardens or crop fields Pesticides are generally effective but can be very dangerous if used incorrectly

Pesticide Regulation In most countries, in order to sell or use a pesticide, it must be approved by a government agency, in the US, it’s the Environmental Protection Agency (EPA) Complex and costly studies must be conducted to decide whether the material is safe to use and effective against the intended pest. During the registration process, a label is created which contains directions for the proper use of the material. Based on toxicity, pesticides are assigned to a Toxicity Class.

Pesticide Regulation Some pesticides are considered too hazardous for sale to the general public and are designated RESTRICTED USE Pesticides Only certified applicators, who have passed an exam, may purchase or supervise the use of restricted use pesticides. Records of sales and use are required to be maintained by government agencies charged with the enforcement of pesticide regulations.

Soil Fertility Fertile soil contains nutrients that are necessary for basic plant nutrition – Nitrogen Phosphorus and Potassium are important elements in fertile soil Also contains sufficient minerals for basic plant nutrition – Boron, Chlorine, Cobalt, Copper, Iron, Magnesium, etc. Soil pH is between 6.0 and 6.8

SUMMARY As you can see, there are many different uses for chemicals in agriculture today Some chemicals are helpful, but some can be very dangerous, and only professionals are allowed to handle them You should always be very cautious when handling chemicals, never smell, taste, inhale or touch them directly.